When a clinical examination is conducted to analyze constituents of blood, urine, or other biological sample of a patient, the sample is caused to react with a reagent to perform qualitative/quantitative analysis of a target constituent. In this instance, a liquid supply mechanism called a dispensing mechanism is used to supply predetermined amounts of sample and reagent liquids to a reaction vessel in which the sample reacts with the reagent. The liquid supply mechanism causes a nozzle to suction a target liquid by producing a negative pressure within a nozzle with use of a syringe, diaphragm, or other pressure change means for the suctioning, and then discharges a predetermined amount of the liquid to the reaction vessel by producing a positive pressure within the nozzle by using the pressure change means.
The nozzle is washed after a sample and a reagent are suctioned and discharged because the nozzle will be used to dispense a different sample and a different reagent. External washing and internal washing are performed for nozzle washing purposes. In external washing, the nozzle is washed by pouring a washing solution onto the outer surface of the nozzle. In internal washing, the interior of the nozzle is washed by allowing the nozzle to discharge the washing solution. If the washing solution is used up before the completion of a nozzle washing process, the results of analysis are adversely affected due to insufficient washing. In view of such circumstances, a system described in Patent Document 1 detects the presence of the washing solution, and issues a warning when the washing solution is about to run short.